A vacuum carburizing furnace, which is a kind of a carburizing device, is disclosed in the following Patent Document 1. In the vacuum carburizing furnace, a thermal insulation material made of a ceramic is provided to surround a workpiece (a treatment target) inside a furnace body. In addition, a furnace bed on which the workpiece serving as a carburizing target object is mounted is provided in a lower part inside the furnace body, and a radiant tube (a heat source) made of a ceramic is provided from an upper part inside the furnace body through left and right sides of the workpiece. In such a vacuum carburizing furnace, when a hydrocarbon-based gas, as a carburizing gas, is supplied into the furnace body and an inside of the furnace body is under a high-temperature environment of 500 to 600° C., carbon obtained by thermal decomposition of the carburizing gas penetrates into a surface of the workpiece (carburization).
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2006-112770
The thermal insulation material and the radiant tube inside the furnace body have a relatively simple shape and are made of a ceramic. On the other hand, the furnace bed has a relatively complex shape and is generally made of a metal in consideration of processability. That is, in a carburizing device of the related art, since components inside the furnace body are made of different materials, durability (a durability lifespan) of the components is different for each material, and therefore a maintenance cycle of the components is different for each material.
However, when the maintenance cycle of the components is different for each material in this manner, since a maintenance plan becomes complicated, there may be a problem of usability. Users who operate the carburizing device and perform various workpiece processes strongly demand simple maintenance in order to improve an operation rate of the carburizing device as much as possible.